The 455 Olds LOOKS the same as the 260/307/350/400 Olds engine, but it's 1" taller, and 1 1/2" wider than the other engines. I found that out the hard way trying to install a customer-supplied used engine.

The 500 Cadillac (early to mid-70's) is one of the best swaps, more powerful, and lighter weight than the Olds engines.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!